Answer: The right answer is the D) People who are unsure what organic produce is.
Explanation: Just to elaborate a little on the answer, it can also be added that the article hasn't been likely written for organic gardeners, since they are mentioned in it ("organic gardeners think of their plants as part of a whole system in nature"). In addition, it hasn't been likely written for people who eat organic food, since it defines what organic is and it starts by saying "you may have wondered why [organic produce] is displayed separately from the rest." Finally, it hasn't been likely written for managers in grocery stores, since they are the ones that write and place the labels, and not the ones that notice them and wonder what they mean. The audience of this article is, therefore, people who are unsure what organic produce is, and who are provided with a clear and explanatory definition.